Ab0072 Prophylactic Efficacy of Tixagevimab-Cilgavimab in Rituximab-Treated Patients With Autoimmune Rheumatic Diseases

Background: Individuals with autoimmune rheumatic diseases (ARDs) that are receiving treatment with rituximab (RTX) are at higher risk of severe outcomes upon infection with SARS-CoV-2 [1,2]. However, limited data exist regarding the efficacy of Tixagevimab-Cilgavimab (Tix-Cil) prophylaxis in preventing COVID-19 in such patients [3,4]. Objectives: To investigate the efficacy and safety of Tix-Cil in preventing SARS-CoV-2 infection in RTX-treated ARD patients. Methods: Between October and December 2022, Tix-Cil was administered to 37 ARD patients under chronic RTX treatment. Over six months, data on demographics, vaccination status, adverse events, and breakthrough infections were collected. Multivariate logistic regression analysis was conducted to identify possible factors associated with COVID-19 infection. Results: The median age (IQR) of the population was 53 (45.5- 61.5) years, and the majority (89.2%) of the participants had prior vaccination with at least two doses of a SARS-CoV-2 vaccine. Females accounted for 78.4% of the patient cohort. Smoking habits varied, with 6 (16.2%) being current smokers and 13 (35.1%) being ex-smokers. Systemic Sclerosis was the most common ARD (24.3%), followed by ANCA associated Vasculitis (16.2%). Comorbidities were prevalent in the cohort, with hypertension, dyslipidemia, and obesity to be found in 29.7% of the cases respectively. Notably, 91.9% of patients received prednisone treatment, with a median dose of 5 mg. Regarding concomitant treatment, 51.4% of the patients were treated with Mycophenolate Mofetil and other medications such as Hydroxychloroquine and Methotrexate at lower rates. The median (IQR) interval between Tix-Cil administration and RTX treatment was 6 (3.5-6) months. In our cohort, six patients (16.2%) were diagnosed with a confirmed SARS-CoV-2 infection, following a median (IQR) of 2 (2.5-4) months after Tix-Cil administration. Variant determination was available for 4/6 (66,7%) patients and identified Omicron variants in all cases. Two patients had the BA.5 variant, and two had the BA.2 variant. A history of prior COVID-19 infection accounted for 51.4% of cases among infected participants, indicating incomplete protection against new variants. Severe cases were uncommon. The most common adverse events reported related to Tix-Cil administration were injection site pain (25%) or headache (15%). No serious adverse events were reported during the observational period. Conclusion: In this single-center prospective study, pre-exposure prophylaxis with Tix-Cil effectively mitigated the risk of SARS-CoV-2 infection in ARD patients undergoing RTX treatment. Moreover, the incidence of breakthrough infections was observed to be low. The study provides valuable insights into the possible prophylactic interventions associated with breakthrough infections and underscores the need for further research to refine recommendations for this vulnerable population. REFERENCES: [1] Grainger R, et al. Nat Rev Rheumatol 2022; 18:191-204. [2] Rutter M, et al. 2022;61:3161-3171. [3] Al-Obaidi MM, et al. Am J Med 2023; 136:96-99. [4] Thomas M, et al. Rheumatology (Oxford) 2023: kead449. Acknowledgements: NIL. Disclosure of Interests: None declared.